Ten years of ocean science and conservation online.

Welcome to Volume #4 of Dear Shark Man, an advice column inspired by a ridiculous e-mail I received. You can send your questions to me via twitter (@WhySharksMatter) or e-mail (WhySharksMatter at gmail).

Dear Shark Man,

I feel more and more guilty about my own meat consumption. I wonder, are there any vegan sharks?

Sincerely,
Eager in England

Dear Eager,

There are more than 500 species of sharks, and they range widely in shape, size, habitat, and behavior. However, every single species eats animals. Many eat fish, some eat invertebrates, and few eat mammals and birds, but they all eat animals. Even the filter-feeders like whale sharks are eating zooplankton, which are (tiny) animals.

Bonnethead sharks have been documented with seagrass in their stomachs, which is likely the result of accidentally ingesting seagrass while eating crabs that live among the grass. (Sometimes I fail to pick all the lettuce off of my turkey sandwich and eat it accidentally, that doesn’t mean I’m seeking out lettuce or that lettuce is a major component of my diet). Recent work by Samantha Leigh has shown that bonnetheads may be able to partially digest this seagrass, which is pretty neat. However, that does not make them vegans, or even vegetarians.

Incidentally, a member of an influential marine conservation family whose name rhymes with Mousteau once claimed that there are more than 1,000 species of sharks and most of them are vegetarian, which is…extremely not correct.

Dear Shark Man,

Would it be feasible to actually attach lasers to a shark’s head… and if so… what would be the optimum way a shark could trigger the activation of said laser on its head?

Furthermore, if feasible, could the half-dolphin been lasered in half?

If you wanted to trigger the laser to activate only at key times, something like an accelerometer or tail-beat monitor would probably be best. These tools can detect temporary changes in swimming speed and behavior associated with feeding.

And while there are incredibly strong lasers these days, the power requirements for a laser strong enough to burn through blubber and bone are probably prohibitive for a portable model small enough to fit on a friggin’ shark. For now, anyway.

There are an enormous variety of different shark species, and they live all over the world, so it really depends on which population of which species you’re asking about. Ganges river sharks participate in Kumbh Mela, while lesser spotted dogfish off Northern Ireland generally prefer Catholic holidays. Sharks tend not to celebrate Father’s Day, because of complications associated with parthenogenesis (mother sharks can sometimes self-clone without the aid of a male) and multiple paternity (a littler of sharks born at the same time can be half-siblings with different fathers). In general, though, sharks are happy to join in any celebration, as long as there’s food involved, and as long as dancing is not required.

During my Masters, however, I worked for a state natural resources management agency that was regularly asked to generate data for fisheries management plans. Such studies often require lethal sampling,and I was present on the research vessel while a couple of hundred sharks were sacrificed for various ongoing studies. I personally sacrificed two sharks, and found that while I recognized the value of such data, I really did not enjoy it and left that task to others. (For what it’s worth, these studies were all on species that aren’t threatened like bonnethead and finetooth sharks, and the lab I worked in took great pains to share samples with other labs so that more sharks didn’t need to be sacrificed).

If you’re asking how many sharks have unintentionally died as a result of my research due to capture stress, the answer is probably dozens, almost all during my Masters research. (The sampling gear we used there, longlines and gill nets, is more stressful to sharks than the drum lines my Ph.D. lab used).

Also, I have eaten shark, but I never killed one to eat it.

That’s it for Volume #4 of Dear Shark Man! Keep your Dear Shark Man questions coming, and be sharky to each other!

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